A new laboratory test chamber for the determination of diffusive sampler performances

International audienceA new laboratory test chamber has been developed at INERIS for the determination of diffusive sampler performance. It consists in a loop made of glass, stainless steel and PTFE containing the reference atmosphere where diffusive samplers are exposed. It is possible to accommodate several samplers simultaneously and simulate various environmental conditions such as temperature, wind speed, wind direction, humidity, atmosphere composition, total pressure and exposure duration. Ail working parameters are continuously monitored. It is shown that certain environmental conditions can deeply affect diffusive sampler performances. Thanks to the technical solutions adopted for its design, this chamber allows the determination of diffusive sampler performance in a wide range of experimental conditions in compliance with the new standards for the monitoring of ambient air by diffusive means

Influence of vehicle traffic reduction in a town centre on BTX pollution

International audienceOn September 22nd 1998, 35 French towns took part in a pilot experiment consisting in drastically reducing the vehicle traffic in the town centres. According to that scheme, INERIS, in association with the local Air Quality Monitoring Network AIRLOR, carried out a BTX sampling campaign over 3 days, in order to quantify the impact of the traffic restrictions on air quality. This campaign was carried out in the centre of Nancy, where traffic restrictions were imposed on an extensive area. Sampling sites were chosen close to the busiest traffic routes. Sampling was carried out using passive samplers, on 10 hours on each day of the campaign. Measurements show clearly that, over the 3 days, the traffic flow reduction led to a decrease in BTX roadside concentrations by between 30 to 80 %. These measurements correlate well with CO levels monitored at one of the sampling sites, and with the volume of traffic in circulation each day. The correlation between BTX and CO clearly indicates traffic as the main source of atmospheric pollution. Measured benzene levels over the 3 days are compared with statutory limit values in France and in Europe

Air quality monitoring and modelling techniques for street canyons : the Paris experience

A better understanding of the dispersion and transformation of atmospheric pollutants in urban micro-environments is required to address the increasing public concern about human exposure in such areas. A joint research program has been established between INERIS (France) and University of Greenwich (UK) with the aim of developing efficient air quality monitoring and modelling methodologies to cover the needs of public health and road traffic managers in Europe. An intensive monitoring campaign was conducted at a representative canyon street in Paris in winter 1998. This experiment was designed to establish the spatial and temporal variation of pollution within the canyon, and test readily available dispersion models. Active and passive techniques were used to sample a wide range of traffic generated pollutants (VOC and inorganic gases) at different heights and distances from the kerb. Local meteorological and traffic information was also obtained. The observed CO and NO concentrations were compared with predicted values, calculated using AEOLIUS, the street canyon model developed by the UK Meteorological Office. The results demonstrate strong spatial pollution gradients within the canyon, large differences between roadside and background pollution levels, and pronounced temporal variability

BTX passive sampling to characterise traffic restriction effects

International audienceOn September 22 of each year a large number of French and European towns reduce the motor vehicle traffic in their city centre. Diffusive sampling of benzene, toluene and xylene during periods of 10 hours was used to characterise the improvement of the air quality due to these traffic restrictions. Despite the short sampling duration the use of diffusive sampling led to results consistent with the reduction of the number of motor vehicles and the measured concentrations of carbon monoxide. While under normal traffic conditions most benzene roadside concentrations measured during the day under low wind speed conditions exceeded the European limit value of 5 ug/m3 , these concentrations decreased to an average of 1.5 u.g/m3 under restricted traffic conditions with only 2 out of 10 measurement sites showing concentrations exceeding the French air quality target value of2 ug/m3

A weighted sum parameter to simplify discussion on aldehyde exposure

In the present work, the personal exposure of a French urban population to several aldehydes is assessed. For this purpose, a weighted sum parameter is used which takes into account the differences in sensory irritation of aldehydes. The personal exposure of 17 volunteers was assessed with personal passive samplers during one week. Simultaneously, aldehyde concentrations were determined in different microenvironments. The results show that formaldehyde is the most important sensory irritant of the aldehydes included in this study, due to a particularly high sensory irritation and because it is a ubiquitous compound found at high concentrations. Personal exposure is strongly linked to indoor exposure (homes and offices). By using a weighted sum parameter, the discussion of large data sets is considerably simplified. This sum parameter could be easily extended to other strong sensory irritants, leading to a weighted TVOC value for sensory irritation

Environmental benzene exposure assessment for parent-child pairs in Rouen, France

International audienceThere is a lack of data on environmental benzene exposure in children. In this study, we compared personal benzene exposure and inhalation uptake in a group of children to those of their parents. We also compared levels of urinary benzene metabolites, trans, trans-muconic acid (MA) and hydroquinone (HQ), for those two groups, and assessed the correlation between personal benzene exposure and urinary MA and HQ concentrations. The study was performed on 21, 2-3-year-old children and their parents recruited on a voluntary basis among non-smokers from the three largest day-care centers of the town of Rouen in France. Average benzene concentrations were measured over 5 consecutive days with diffusive. samplers. The following simultaneous measurements were carried out: personal exposure of the parents, concentrations inside and outside the day care centers, and inside the volunteer's bedrooms. Morning and evening urine samples were collected during the same period. Benzene personal exposure levels were 14.4 +/- 7.7 mug/m(3) and 11.09 +/- 6.15 mug/m(3) in parents and children, respectively. Benzene inhalation uptake estimates were 2.51 +/- 1.23 mug/kg/day in the group of parents and 5.68 +/- 3.17 mug/kg/day in the group of children. Detectable levels of MA and HQ were found in 85% and 100% of the samples, respectively. Intra-individual variation of urinary MA and HQ concentrations expressed as a coefficient of variation (CV) ranged from 63 to 232% and from 13 to 144%, respectively. Mean values of MA and HQ (in mg/g creatinine) were 1.6- and 1.8-fold higher in the group of children than in the group of parents (P=0.008 and P<0.0001, respectively). Significant correlations between metabolites levels and benzene were not found

Analyses and Validation of Conditional Dependencies with Built-in Predicates

This paper proposes a natural extension of conditional functional dependencies (CFDS [14]) and conditional inclusion dependencies (CINDS [8]), denoted by CFD(p)s and CIND(p)s, respectively, by specifying patterns of data, values with not equal, &lt;, &lt;=, &gt; and &gt;= predicates. As data quality rules, CFD(p)s and CIND(p)s are able to capture errors that commonly arise in practice but cannot, be detected by CFDS and CINDS. We establish two sets of results for central technical problems associated with CFD(p)s and CIND(p)s. (a) One concerns the satisfiability and implication problems for CFD(p)s and CIND(p)s, taken separately or together. These are important for, e.g., deciding whether data, quality rules are dirty themselves, and for removing redundant rules. We show that despite the increased expressive power, the static analyses of CFD(p)s and CIND(p)s retain the same complexity as their CFDs and CINDs counterparts. (b) The other concerns validation of CFD(p)s and CIND(p)s. We show that given a set Sigma of CFD(p)s and CIND(p)s on a database D, a, set of SQL queries can be automatically generated that, when evaluated against D, return all tuples in D that violate some dependencies in Sigma. This provides commercial DBMS with an immediate capability to detect errors based on CFD(p)s and CIND(p)s.Computer Science, Information SystemsComputer Science, Theory &amp; MethodsEICPCI-S(ISTP)